Revert "Roll recipe dependencies (trivial)."

This reverts commit 6c2b2bb.

Reason for revert: breaks presubmit

Original change's description:
> Roll recipe dependencies (trivial).
> 
> This is an automated CL created by the recipe roller. This CL rolls recipe
> changes from upstream projects (e.g. depot_tools) into downstream projects
> (e.g. tools/build).
> 
> 
> More info is at https://goo.gl/zkKdpD. Use https://goo.gl/noib3a to file a bug.
> depot_tools:
>   https://crrev.com/e1410883a38ac3a3491ed470883ec405193442f6 depot_tools: Add httplib2 to .vpython (ehmaldonado@chromium.org)
> 
> 
> TBR=borenet@google.com
> 
> Recipe-Tryjob-Bypass-Reason: Autoroller
> Bugdroid-Send-Email: False
> Change-Id: Ie3096ecfdaeb0db9e4e68550dcf77298225cd0f9
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247797
> Reviewed-by: Recipe Roller <recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com>
> Commit-Queue: Recipe Roller <recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com>

TBR=borenet@google.com,recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com

Change-Id: I46fd0ea3d098aa101034b97c223993fe5514e345
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/247958
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Eric Boren <borenet@google.com>

Author: erock2112

infra/config/recipes.cfg

@@ -14,7 +14,7 @@
   "deps": {
     "depot_tools": {
       "branch": "master",
-      "revision": "e1410883a38ac3a3491ed470883ec405193442f6",
+      "revision": "b2b51418596ec5465a49405a36b6dee55c42488d",
       "url": "https://chromium.googlesource.com/chromium/tools/depot_tools.git"
     },
     "recipe_engine": {